Terpene-phosphorous pentasulfidesulfur lubricating oil additive



Patented Sept. 21, 1954 3 TER'PENE-PHOSPHOROUS PENTASULFIDE- SULFURLUBRICATING OIL ADDITIVE Lindley C. Beegle, Stamford, Conn., assignor toAmerican Cyanamid Company, New York, N. Y., a corporation of Maine NoDrawing. Application December 14, 1949, Serial No. 132,995

4 Claims.

The present invention relates to a novel class of additives forhydrocarbon lubricating oils. It relates more particularly to a class ofphosphorous and sulfur-containing compounds which have been found to beparticularly useful as antioxidants and anticorrosion agents forhydrocarbon oils. The invention includes the compounds themselves, themethod of their preparation, and their use as hydrocarbon-lubricatingoil additives.

The art has recognized that phosphorous and sulfur-containing compoundsare, in general, effective in preventing the oxidation of highly refinedhydrocarbon lubricating oils in internal combustion engines and inpreventing the corresion of the moving engine parts. The industry haspreviously employed lubricating oil additives prepared from variousphosphorous and sulfurcontaining compounds such as phoshorouspentasulfide, phosphorous sesquisulfide, andthe like compounds. Theadditives have usually consisted of neutral metal salts of the productsof reaction of these phosphorous and sulfur-containing compounds withvarious organic materials. For example, phosphorous pentasulfide hasbeen alkylated, or reacted with various phea nolic bodies, and thereaction products have been neutralized with metal oxides or hydroxidesin the preparation of useful lubricating oil additives.

More recently, it has also been suggested that a useful class oflubricating oil additives might be prepared by reacting various terpeneswith phosphorous pentasulfide. In most instances these reaction productshave been further condensed with aliphatic and/or aromatic compounds. Ingeneral, this type of additive has been said to provide satisfactoryprotection against oxidation of hydrocarbon lubricating oils undernormal operating conditions of internal combustion engines.

I have discovered that a novel class of hydrocarbon lubricating oiladditives which possess greatly improved antioxidant and anticorrosionproperties may be prepared by reacting phosphorous pentasulfide andvarious bicyclic terpenes with sulfur or a sulfurizing agent. Theadditional reacted sulfur in my novel additives greatly increases thedesirability thereof over the prior art additives by virtue of theirimproved antioxidant and anticorrosion properties. The products, as willhereinafter be shown, provide a much greater degree of protection in thelubrication of internal combustion enginesv by preventing excessivecorrosion of the moving parts and by substantially eliminating oxidationof the lubricants employed therein.

It has been found that any of the bicyclic terpenes, namely thosebicyclic hydrocarbons having the general formula ClOHlS, may be used inpreparing the novel lubricating oil additives of the present invention.For example, satisfactory terpenes include alpha-pinene, beta-pinene,camphene, bornylene, nopinene (isomeric betapinene), fenchene, thujene,sabinene, carene, and the like bicyclic terpenes. The ordinarycommercial grades of turpentine, most of which contain or more ofalpha-pinene, are also included within the scope of the term bicyclicterpenes as employed in the present invention.

In preparing this novel class of lubricating oil additives, the selectedterpene may be reacted with phosphorous pentasulfide and an additionalsulfur-providing compound under relatively elevated temperatures andunder atmospheric pressure. Ordinarily, the other components are addedto the terpene constituent since the bicylic terpenes are commonlyliquids. While there is no upper limit as to the amount of terpene whichmay be employed, other than that of economic practicability, it isusually advantageous to employ only a small excess of terpene over thestoichiometric requirement to facilitate handling of the reactionproduct. For example, while only about 4 mols of terpene can be reactedwith one mol of phosphorous pentasulfide, it has been found that 6 molsof terpene will provide sufiicient liquid vehicle to permit easyhandling of the reaction product.

While various sulfurizing agents may be employed in my reaction,elemental sulfur is the preferred material since its use eliminates thenecessity of removing contaminating by-products or unreacted materials.It has been found that the amount of sulfur which may be reacted withthe selected terpene and phosphorous pentasulfide is within the range offrom about 0.5 mol to about 3 mols for each mol of P285 present. Whileamounts smaller than 0.5 mol per mol of P285 may be used, the increasein antioxidant properties of the reaction product is not sulficientlysubstantial to be of economic desirability. On the other hand, althoughthe presence of relatively large amounts of sulfur in the lubricatingoil. additives is sometimes desirable, the presence of more than aboutv3 mols thereof for each mol of PzSs causes crystalline material tosettle out of the lubricating oil additive upon storage.

A primary feature of the present invention therefore, resides inthereaction of about 4 mols of a bicyclic terpene with one mol ofphosphorous pentasulfide and with from about 0.5 mol to about 3 mols ofsulfur. If desired, the sulfur, P255, and terpene may be reactedtogether. However, it has also been found that the terpene and P2S5 maybe first reacted, and then the sulfur may be added and the mixturefurther reacted. Solvent extraction of the final reaction product hasshown that the sulfur has reacted with the other components and is notmerely in physical combination therewith.

The reaction between the terpene, PzSs, and sulfur is mildly exothermicand may be easily carried out by heating the components to from about 80C. to about 90 C. and thereafter controlling the reaction temperature asdesired according to the particular type of equipment employed. When anopen reaction vessel is employed under atmospheric conditions, it ispreferable that the reaction temperature be maintained below about 160C. in order to prevent excessive evaporation of the terpene. On theother hand, where reflux equipment is used, superatmospheric pressuresand more elevated temperatures may be resorted to if it is so desired.The reaction products in either instance are normally dark colored,relatively viscous liquids which are readily soluble in hydrocarbonlubricating oils. Although numerous of the common organic solvents maybe employed, as hereinbefore stated it is preferable to use an excess ofthe particular terpene employed in order to facilitate handling of thecomponents during and subsequent to the reaction.

The novel lubricating oil additives of this invention may be employed inlubricating oils in amounts of from about 0.25% to about 2-3% or more,depending on the particular lubricating oil employed and its tendency tooxidize under use in internal combustion engines. However, it has beenfound that ordinarily the use of from about 0.5% to about 1.25% of theadditive, by weight, entirely satisfactorily inhibits oxidation of mostlubricating oils. My novel additives may be employed alone or inconjunction with other antioxidants or detergents. For example,antioxidant compositions which have been found to be particularlysuitable for use with the terpene-PzSs-sulfur reaction products includethe metal salts of esters of dithiophosphoric acids such as bariumdioctyl dithiophosphate, zinc dihexyl dithiophosphate, barium didodecyldithiophosphate, and the like metal dialkyl dithiophosphates. Detergentswhich are particularly suitable include the metal salts of petroleumsulfonates such as calcium petroleum sulfonate, and the like, alkylatedaromatic sulfonates such as calcium or barium dodecyl phenyl sulfonate,and the like; and metal salts of phenol sulfides and disulfides such ascalcium, barium, and zinc salts of dioctyl phenol sulfide, diamyl phenolsulfide, and barium and calcium meta-, ortho-, and para-octyl phenolsulfides.

The invention will be further illustrated by the following specificexamples. It should be understood, however, that although these examplesmay describe certain specific features of the invention, they are givenprimarily for purposes of illustration and the invention, in itsbroadest aspects, is not limited thereto.

EXAMPLE 1 To 408 grams (3 mols) of alpha-pinene, with stirring, wasadded 111 grams (0.5 mol) of P285 and 32 grams (1 mol) of sulfur. Themixture was heated for 2.5 hours at approximately 125 C. Thereafter, 300grams of SAE 10 grade hydrocarbon lubricating oil and 10 grams of adiatomaceous earth filter aid was added to the reacted material, afterwhich the excess alphapinene was stripped off at a temperature of 125 C.and 12-15 mm. Hg. The oil concentrate was then filtered. To the product,which weighed 410 grams, was added grams additional SAE '10 gradehydrocarbon lubricating oil to produce a 50% concentrate in oil of theproduct. The reaction product contained 3.6% of phosphorous and 14.0% ofsulfur.

A sample of the product was tested as an antioxidant by the Underwoodcorrosion test using cadmium-silver alloy bearings as test material. A1500 cc. sample of a Mid-Continent base lubricating oil of SAE: 30 gradecontaining 0.4% by weight of the additive and 0.04% of iron naphthenate,based on the FezOs equivalent, as oxidation catalyst was heated for 10hours at 325 F. while continuously spraying portions of the oil againsttwo freshly sanded alloy bearings, the apparatus being so constructed asto permit free circulation of air. The total bearing loss was 4milligrams, whereas the loss with a sample of the same oil containingthe same quantity of iron naphthenate but no antioxidant was 1236milligrams, while the oil viscosity increased over 300%. A samplecontaining a similar quantity of a P2S5alpha-pinene reaction productprepared as described above but with no additional sulfur had a totalhearing loss of 495 milligrams and a viscosity increase of 79%.

EXAMPLE 2 To 408 grams (3 mols) of alpha-pinene, with stirring, wasadded 111 grams (0.5 mol) of P285 and 8 grams (0.25 mol) of sulfur. Themixture was heated to l20-125 C. and maintained at a temperature below143 0., the heating being continued for a period of 25 hours. Thereafterthe reaction product was diluted with light grade, refined minerallubricating oil, stripped, filtered, and prepared as a 50% concentratein oil as described in Example 1. The product weighed 357 grams andcontained 4.36% phosphorous and 12.46% of sulfur and was readily solublein hydrocarbon lubricating oils.

EXAMPLE 3 To 408 grams (3 mols) of alpha-pinene, with stirring, wasadded 111 grams (0.5 mol) of P285 and 48 grams (1.5 mol) of sulfur. Themixture was heated for 2.5 hours at -125 C. Thereafter, the reactionproduct was diluted with mineral lubricating oil, stripped, filtered,and prepared as a 50% concentrate in oil according to the proceduredescribed in Example 1. The product weighed 424 grams and contained3.67% of phosphorous and 15.1% of sulfur.

A sample of the product was added to a Mid- Continent base SAE 30 gradelubricating oil to a 0.4% solution of the additive. The bearingcorrosion loss was slightly greater than 1 milligram and the treated oilincreased 19.5% invis cosity when the oil was tested as described inExample 1. A control sample of the product of reaction of Pass andalpha-pinene had a bearing corrosion loss of 2844 milligrams when testedin a similar fashion, while the viscosity of the oil increased EXAMPLE 4Four samples were prepared as follows: Alpha.- pinene was charged to aglass lined kettle and heated to about 115-1'20 C. Pest and sulturweredry mixed and added to the heated pinene over a relatively extendedperiod of time to prevent loss of starting materials by virtue of theexothermic reaction. The mixture was thereafter heated until reactionwas -.-substantially complete. Then a light grade (SAE 10), highlyrefined lubricating oil was added to .the product i501 convenience insubsequent handling, after which the :excess alpha-pinene was strippedoff under vacu- :um at about 100-140 0. Additional SAE 10 gradehydrocarbon oil was then added to prepare a 50% concentration of theproduct in oil and the concentrate was filtered. The condi- 6 tested :asdescribed in-Example 1, while the bear ing corrosion loss of a controlsample of oil containing no additive was 1600 milligrams.

EXAMPLE 6 To 408 grams of beta-pinene, with stirring, was added 111grams of P2S5 and 48 grams of sulfur. The mixture was heated to 80-90 C.and maintained at a temperature not greater than about 120-130 C. for2.5 hours. Thereafter the reaction product was diluted with SAE 10 grademineral lubricating oil, stripped at 135 C., filtered and prepared as a50% concentrate in oil as described in Example 1.

tions under which these four samples were pre- '15 A sample of the aboveproduct was added to a pared are tabulated below in Table I.Mid-Continent base SAE 30 grade lubricating oil Table I Quantity ofReactants,

Pounds Past-S Average Reaction Strip- Yield Sam 18 No Addition ReactionTime ping of p Temp., Temp., Minuts Time, Product,

Alpha- P S S 0. 0. Minutes Lbs. Pinene 2 A s1. 6 22. 5 6.4 120 114 110105 82 B s1. 6 22. s e. 4 115 114 165 70 81 o s1. 6 22. s e. 4 117 129245 90 85 1) 3,920 1,067 307.5 119 155-160 240 220 4,560

The above samples were tested by incorporation in a Mid-Continent baselubricating oil of SAE grade 30 in amounts of 0.75% to 1.0% by weight.

The treated oil was subjected to actual operating conditions in aChevrolet automobile engine for a 36 hour continuous run, the enginebeing run at 3.150 R. P. M. under a load of 30 brake horsepower with acrankcase temperature of 280 F. and a jacket temperature of 180200 F.The engine was thereafter dismantled and examined for bearing corrosion,and the oil was tested for viscosity and neutralization number increase.The neutralization number was determined as the number of milligrams ofKOH required to exactly neutralize one gram of oil containing the aboveadditives. Test results were as fol- IOWSZ Table II Concentrationpercent by Weight Baring/ Neut' liercengs orrolSCOSl y Sample sion, gml/increase Terpene- Deterbearing New Used at 100 F.

Pas -S gent 1 0 2. 677 neut. 2. 7 41 1.0 0 0.017 0.1 1.3 22 0. 8 0 0.028 0. 1 1. 4 30 0. 8 0 0. 016 0. 1 1. 6 28 0. 8 0 0. 039 0. 1 1. 831 1. 0 2.0 0.033 0.6 0.7 6 0. 2. 8 0. 084 0. 9 0. 9 13 0. 8 O. 8 0. 0290. 2 0. 7 12 1 The detergent employed was a barium salt of an alkylatedphenol sulfide.

EXAMPLE 5 To 161 gram of camphene, with stirring, was added 44 gramsP2S5 and 12.3 grams of sulfur. The mixture was heated to 120130 C. andmaintained at this temperature for 2.5 hours. Thereafter the reactionproduct was diluted with SAE grade mineral lubricating oil, stripped at135 C., filtered, and prepared as a 50% concentrate in oil as describedin Example 1.

A sample of the product was added to a Mid- Continent base SAE gradelubricating oil to a 1.0% solution of the additive. The bearingcorrosion loss was 0.0 milligram when the oil was to a 1.0% solution ofthe additive. The bearing corrosion loss was 0.0 milligram when the oilwas tested as described in Example 1, while the bearing corrosion lossof a control sample of oil containing no additive was 1600 milligrams.

EXAMPLE 7 To 408 grams of steam distilled turpentine was added 111 gramsof P285 and 32 grams of sulfur. The mixture was heated and maintained ata temperature of 120-130 C. for 2.5 hours. Thereafter, the reactionproduct was diluted with SAE 10 grade mineral oil, stripped at 130 C.,filtered and prepared as a 50% concentrate in oil.

A sample of the product was added to a Mid- Continent base SAE 30 gradelubricating oil to 0.75% solution of the additive. The bearing corrosionloss was 3'7 milligrams when the oil was tested as described inExample 1. The viscosity of the oil increased during the test periodwhile the neutrality number increased from 0.1 to 4.0.

I claim:

1. A method 'of preparing a hydrocarbon lubricating oil antioxidantwhich comprises simultaneously reacting together a bicyclic terpene,phosphorous pentasulfide, and elemental sulfur at a temperature range offrom about C. to about C. for a period of time not substantiallyexceeding four hours, the reactants being employed in the proportion ofat least about 4 mols of the bicyclic terpene and from about 0.5 toabout 3 mols of sulfur for each mol of phosphorous pentasulfide.

2. A method of preparing a hydrocarbon lubricating oil antioxidant whichcomprises simultaneously reacting together alpha-pinene, phosphorouspentasulfide, and elemental sulfur at a temperature range of from about115 C. to about 130 C. for a period of time not substantially exceedingfour hours, the reactants being employed in the proportion of at leastabout 4 mols of alpha-pinene and from about 0.5 to about 3 mols ofsulfur for each mol of phosphorous pentasulfide.

3. A method of preparing a hydrocarbon lubricating oil antioxidant whichcomprises simultaneously reacting together beta-pinene, phosphorouspentasulfide, and elemental sulfur at a temperature range of from about115 C. to about 130 C. for a period of time not substantially exceedingfour hours, the reactants being employed in the proportion of at leastabout 4 mols of beta-pinene and from about 0.5 to about 3 mols of sulfurfor each mol of phosphorous pentasulfide.

4. A method of preparing a hydrocarbon lubricating oil antioxidant whichcomprises simultaneously reacting together camphene, phosphorouspentasulfide, and elemental sulfur at a temperature range of from about115 C. to about 130 C. for a period of time not substantial- 1yexceeding four hours, the reactants being employed in the proportion ofat least about 4 mols of camphene and from about 0.5 to about 3 mols ofsulfur for each mol of phosphorous pentasulfide.

References Cited in the file Of this patent UNITED STATES PATENTS NumberName Date 2,316,087 Gaynor Apr. 6, 1943 2,379,453 Noland July 3, 19452,413,648 Ott Dec. 31, 1946 2,455,668 Fuller et al Dec. 7, 19482,486,188 May Oct. 25, 1949 2,515,222 Hoock July 18, 1950 2,571,737Manteuffel et a1. Oct. 16, 1951 2,580,430 Hughes et al Jan. 1, 1952

1. A METHOD OF PREPARING A HYDROCARBON LUBRICATING OIL ANTIOXIDANT WHICHCOMPRISES SIMULTANEOUSLY REACTING TOGETHER A BICYCLIC TERPENE,PHOSPHOROUS PENTASULFIDE, AND ELEMENTAL SULFUR AT A TEMPERATURE RANGE OFFROM ABOUT 115* C. TO ABOUT 130* C. FOR A PERIOD OF TIME NOTSUBSTANTIALLY EXCEEDING FOUR HOURS, THE REACTANTS BEING EMPLOYED IN THEPROPORTION OF AT LEAST ABOUT 4 MOLS OF THE BICYCLIC TERPENE AND FROMABOUT 0.5 TO ABOUT 3 MOLS OF SULFUR FOR EACH MOL OF PHOSPHOROUSPENTASULFIDE.